North Korean leader Kim Jong Un has made his first public appearance in more than 40 days, with a visit to a new housing development.

Rodong Sinmun newspaper has published new photos of Kim Jong Un for the first time in more than 40 days Credit: RTV

The 31-year-old has not appeared in public since attending a concert with his wife on September 3 - missing an important political anniversary on Friday as well as a recent session of the country's parliament.

His absence fuelled speculation of ill-health or possible political turbulence in the secretive country, but today the country's official newspaper Rodong Sinmun, printed multiple photos of a smiling Kim standing with the apparent aid of a walking stick.

Multiple images of Kim Jong Un show him being supported by a walking stick Credit: RTV

Last week a source with access to the North's leadership told reporters that Kim was in firm control of the country but had hurt his leg taking part in a military drill.

Today's newspaper report did not say when the visit had been made, or refer to Kim's unusually lengthy absence from public view.

North Korean officials joined grieving relatives at the site of the building collapse. Credit: AP

North Korean officials have joined bereaved families and residents in mourning those killed when a building collapsed in Pyongyang last week.

Korean state media gave no death toll but said that the accident was "serious". Credit: AP

The country's government today offered a rare public apology over the accident, saying the construction of the apartment "was not done properly" and officials "supervised and controlled it in an irresponsible manner".

Hundreds may have been killed in the accident, although the figure is not known Credit: AP

North Korean leader Kim Jong-un reportedly suffered deep anguish over a building collapse in Pyongang that left many dead, according to the country's state media.

The Korean Central News Agency said Kim "sat up all night, feeling painful after being told about the accident", South Korea's Yonhap news agency reported.

North Korea authorities issued a rare apology over the accident. Credit: Reuters

A North Korean official added that the leader "instructed leading officials of the party, state and the army to rush to the scene, putting aside all other affairs".

The number of casualties in the accident has not been revealed, although officials in Seoul believe it could be "considerable", Yonhap said.

"In North Korea, it is common that people move into a new apartment even before the construction is completed. About 92 households may have been living in the apartment," a South Korean government official said.

The incident was marked by a rare apology from senior officials, as "the construction of an apartment house was not done properly, and officials supervised and controlled it in an irresponsible manner".